In a known gear pump a pair of meshed straight-cut spur gears are located in a cavity of a housing to define an entrance chamber and discharge chamber. One of the meshed gears is driven or rotated by an external power source, while the other gear is restrained within the housing as an idler and rotates because of its meshing engagement with the externally driven gear. The entrance chamber is connected to a source of fluid through an inlet port and as the meshed gears rotate fluid is drawn into the chamber as adjacent pairs of gear teeth come out of mesh. The fluid drawn-in is transported within the intertooth spaces of gear members. As adjacent pairs of gear teeth come into mesh, fluid is displaced into an exit port which is connected to this discharge chamber. Close tolerances, various seals and the mesh of the gears prevents the commingling of fluid between the entrance chamber and discharge chamber.
U.S. Pat. No. 5,076,770 discloses a floating and stationary bearing structure which seals the entrance chamber from the discharge chamber and substantially eliminates the drag torque experienced by the intermeshing gears. In this structure, pressurized fluid from the discharge chamber acts on the bearing members to provide a clamping force to seal the entrance chamber from the discharge chamber. This structure performs in a satisfactory manner for most applications and yet the wear experienced by the bearings and the loss of efficiency resulting from the clamping force may be unacceptable for some applications.
U.S. Pat. No. 5,252,047 discloses a floating bearing for a pump having a passage through which an intermediate fluid pressure from the intermeshing gears provides a clamping force to seal the entrance chamber from the discharge chamber. This structure performs in a satisfactory manner however their is an added cost in the manufacture of the floating bearing and a peripheral seal which separates the entrance chamber and the discharge chamber and can under some circumstances offer resistance to movement within the cavity.